The party’s manifesto, published on Thursday, commits the next Government to moving Mayoral elections and Police and Crime Commissioner elections to the First Past The Post (FPTP).

MayorWatch has now been told by two well placed Tory sources that the party expects to extend the changes to the London Assembly, a move which could radically alter the body’s political make-up.

The 25 Assembly Members are currently elected by a mix of FPTP constituencies and a ‘top-up’ list which ensures smaller parties who can gain the support or 5% or more of Londoners also gain seats.

It’s understood that changing how AMs are elected could also see constituency boundaries revised and that a public consultation would held before legislation was brought forward to enact the changes.

Depending on the new boundaries, the Liberal Democrats, which currently have just one member but have previously won as many as five seats, could potentially do better under a revised electoral system as much of their vote is concentrated in the South West of London.

However moving to an all-constituency FPTP model would make it significantly harder for parties such as the Greens and UKIP, which are currently represented on the body, from being elected.

Commenting on the plans, Labour AM Tom Copley said moving away from the current system “would be a backwards step” for politics in the capital, adding that a majority of Assembly Members “oppose this change”.

Baroness Jenny Jones, a former Green party AM, commented: “Even if Assembly is larger, we are back to the bad old days of fewer elected radical voices”.

In March AMs passed a motion calling for the current election system to be retained after MPs attempted to pass a Private Member’s Bill eliminating list members.

Speaking at the time, Green party AM Sian Berry said: “London is one of the most diverse cities in the world and needs an Assembly that can speak up for all kinds of Londoners and represent their views.

“People need to be able to vote for what they believe in and to believe their vote counts – and under Proportional Representation this happens.

“Moving to a First Past the Post system where voters are left trying to work out which parties can win, which ones are in the ‘two horse race’ and then going for the least bad option would be a real backwards step.”

Labour’s Len Duvall added: “When Londoners go to the ballot box to vote in the London Assembly elections, they can be sure that – regardless of whether their preferred candidate and party win in their immediate area – their vote will be reflected in the final result, and that they will be represented at City Hall.

“Any changes to our system would need to make the Assembly an even more accurate reflection of the people it serves.”